Le samedi 01 octobre 2011 à 14:16 -0400, starlight@binnacle.cx a écrit :> At 08:44 AM 10/1/2011 +0200, Eric Dumazet wrote:> >In my experience, I have the exact opposite :> >performance greatly improved in recent> >kernels. Unless you compile your kernel to include> >new features that might reduce performance> >(namespaces, cgroup, ...)> > RH has both of the above turned on in the> 2.6.32-71.29.1.el6.x86_64 kernel tested.> > If these are big negatives to network> performance, could you list what should> specifically turned off to maximize> results? Also a recommendation for> the best recent kernel for another> benchmark would be helpful.> > Probably can't convince anyone to deploy a> kernel without commercial support, but if> an alternate compile fixes performance it> might be possible to convince RH to support> the alternative build.>

2.6.32 has a perf tool, that can really help to spot in a few minuteshot spots. That would definitely help to further diagnose what could bethe problem in your workload.

A single patch can have huge performance impact, sometime not noticed.

For example, in 2.6.36, AF_UNIX support for pid namespaces droppedperformance a lot [commit 7361c36c5224 (af_unix: Allow credentials towork across user and pid namespaces)], because of a single atomicoperation, but done on each send() and receive() on a central location.